The two-pronged objective of this project is the preparation of a data book on Inbred and Genetically Defined Strains of Laboratory Animals to meet a critical need for authoritative documentation and ready retrieval of information on genetically inbred strains (such as the mouse and rat, in which a high degree of genetic-trait fixation has been achieved), and on non-inbred strains (such as the hamster, guinea pig, rabbit, and chicken, in which well-defined traits have been established on the basis of uniformity and repeatability). The first objective has been attained with the publication of Part 1 of the volume covering mouse and rat (available in February 1979). The second objective will be reached when Part 2 on the hamster, guinea pig, rabbit, and chicken is completed at the end of July, and published in the autumn of 1979. The tables of data have been selected for inclusion by an expert Advisory Committee whose members also recommended the recognized authorities from whom the material has been obtained. All of the tables will be reviewed by the Advisory Committee members and their colleagues. Thus the user will be provided with expertly selected and carefully evaluated data. A format kept as consistent as possible will facilitate easy comparison of data, and a comprehensive index will provide prompt access to information. The literature citations appended to each table will permit referral to the original source of material, and also can serve as valuable aids in retrieving additional data.